C:/Musimathics_local/Musimat/MusimatChapter9/C091201c.cpp

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#include "MusimatChapter9.h"
MusimatChapter9Section(C091201c) {
Print("*** Permutation ***");
/*****************************************************************************

Permutation

Iterate the supplied sequence in prime order until exhausted, then permute the 
entire row by inc steps and repeat from the beginning.
*****************************************************************************/
        para1(); // Step into this function to continue.
}

Integer permute(IntegerList L, Integer Reference pos,
        Integer Reference count, Integer inc) { 
        Integer curPos = pos;                                                   // save current position
        Integer x = cycle(L, pos, 1);                                   // update pos and get list value
        count = count + 1;                                                              // increment counter
        If (count == Length(L)){                                                // have we output L items from list?
                count = 0;                                                                      // reset count
                pos = curPos + inc;                                                     // permute position for next time
        }
        Return(x); 
}

Static Void para1() {
/*****************************************************************************
Here is an example of invoking permute().
*****************************************************************************/
        Print("*** Permutation ***");
        IntegerList L(10, 11, 12);
        Integer inc = -1;
        Integer pos = 0;
        Integer perm = 0;

        For (Integer i = 0; i < 3 * Length(L); i++)
                        Print(permute(L, pos, perm, inc));

/*****************************************************************************
prints 10, 11, 12, 11, 12, 10, 12, 10, 11. Because inc = –1, it skips back one place in the 
row every time. The trigger for it to skip is when it has output as many elements as are in the list.
*****************************************************************************/
}}

/* $Revision: 1.2 $ $Date: 2006/09/09 06:22:42 $ $Author: dgl $ $Name:  $ $Id: _c091201c_8cpp-source.html,v 1.2 2006/09/09 06:22:42 dgl Exp $ */
// The Musimat Tutorial © 2006 Gareth Loy
// Derived from Chapter 9 and Appendix B of "Musimathics Vol. 1" © 2006 Gareth Loy 
// and published exclusively by The MIT Press.
// This program is released WITHOUT ANY WARRANTY; without even the implied 
// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
// For information on usage and redistribution, and for a DISCLAIMER OF ALL
// WARRANTIES, see the file, "LICENSE.txt," in this distribution.
// "Musimathics" is available here:     http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=10916
// Gareth Loy's Musimathics website:    http://www.musimathics.com/
// The Musimat website:                 http://www.musimat.com/
// This program is released under the terms of the GNU General Public License
// available here:                      http://www.gnu.org/licenses/gpl.txt

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